code: def fcode(expr, assign_to=None, **settings):
      """Converts an expr to a string of fortran code
  
      Parameters
      ==========
  
      expr : Expr
          A SymPy expression to be converted.
      assign_to : optional
          When given, the argument is used as the name of the variable to which
          the expression is assigned. Can be a string, ``Symbol``,
          ``MatrixSymbol``, or ``Indexed`` type. This is helpful in case of
          line-wrapping, or for expressions that generate multi-line statements.
      precision : integer, optional
          DEPRECATED. Use type_mappings instead. The precision for numbers such
          as pi [default=17].
      user_functions : dict, optional
          A dictionary where keys are ``FunctionClass`` instances and values are
          their string representations. Alternatively, the dictionary value can
          be a list of tuples i.e. [(argument_test, cfunction_string)]. See below
          for examples.
      human : bool, optional
          If True, the result is a single string that may contain some constant
          declarations for the number symbols. If False, the same information is
          returned in a tuple of (symbols_to_declare, not_supported_functions,
          code_text). [default=True].
      contract: bool, optional
          If True, ``Indexed`` instances are assumed to obey tensor contraction
          rules and the corresponding nested loops over indices are generated.
          Setting contract=False will not generate loops, instead the user is
          responsible to provide values for the indices in the code.
          [default=True].
      source_format : optional
          The source format can be either 'fixed' or 'free'. [default='fixed']
      standard : integer, optional
          The Fortran standard to be followed. This is specified as an integer.
          Acceptable standards are 66, 77, 90, 95, 2003, and 2008. Default is 77.
          Note that currently the only distinction internally is between
          standards before 95, and those 95 and after. This may change later as
          more features are added.
      name_mangling : bool, optional
          If True, then the variables that would become identical in
          case-insensitive Fortran are mangled by appending different number
          of ``_`` at the end. If False, SymPy Will not interfere with naming of
          variables. [default=True]
  
      Examples
      ========
  
      >>> from sympy import fcode, symbols, Rational, sin, ceiling, floor
      >>> x, tau = symbols("x, tau")
      >>> fcode((2*tau)**Rational(7, 2))
      '      8*sqrt(2.0d0)*tau**(7.0d0/2.0d0)'
      >>> fcode(sin(x), assign_to="s")
      '      s = sin(x)'
  
      Custom printing can be defined for certain types by passing a dictionary of
      "type" : "function" to the ``user_functions`` kwarg. Alternatively, the
      dictionary value can be a list of tuples i.e. [(argument_test,
      cfunction_string)].
  
      >>> custom_functions = {
      ...   "ceiling": "CEIL",
      ...   "floor": [(lambda x: not x.is_integer, "FLOOR1"),
      ...             (lambda x: x.is_integer, "FLOOR2")]
      ... }
      >>> fcode(floor(x) + ceiling(x), user_functions=custom_functions)
      '      CEIL(x) + FLOOR1(x)'
  
      ``Piecewise`` expressions are converted into conditionals. If an
      ``assign_to`` variable is provided an if statement is created, otherwise
      the ternary operator is used. Note that if the ``Piecewise`` lacks a
      default term, represented by ``(expr, True)`` then an error will be thrown.
      This is to prevent generating an expression that may not evaluate to
      anything.
  
      >>> from sympy import Piecewise
      >>> expr = Piecewise((x + 1, x > 0), (x, True))
      >>> print(fcode(expr, tau))
            if (x > 0) then
               tau = x + 1
            else
               tau = x
            end if
  
      Support for loops is provided through ``Indexed`` types. With
      ``contract=True`` these expressions will be turned into loops, whereas
      ``contract=False`` will just print the assignment expression that should be
      looped over:
  
      >>> from sympy import Eq, IndexedBase, Idx
      >>> len_y = 5
      >>> y = IndexedBase('y', shape=(len_y,))
      >>> t = IndexedBase('t', shape=(len_y,))
      >>> Dy = IndexedBase('Dy', shape=(len_y-1,))
      >>> i = Idx('i', len_y-1)
      >>> e=Eq(Dy[i], (y[i+1]-y[i])/(t[i+1]-t[i]))
      >>> fcode(e.rhs, assign_to=e.lhs, contract=False)
      '      Dy(i) = (y(i + 1) - y(i))/(t(i + 1) - t(i))'
  
      Matrices are also supported, but a ``MatrixSymbol`` of the same dimensions
      must be provided to ``assign_to``. Note that any expression that can be
      generated normally can also exist inside a Matrix:
  
      >>> from sympy import Matrix, MatrixSymbol
      >>> mat = Matrix([x**2, Piecewise((x + 1, x > 0), (x, True)), sin(x)])
      >>> A = MatrixSymbol('A', 3, 1)
      >>> print(fcode(mat, A))
            A(1, 1) = x**2
               if (x > 0) then
            A(2, 1) = x + 1
               else
            A(2, 1) = x
               end if
            A(3, 1) = sin(x)
      """
      from sympy.printing.fortran import FCodePrinter
  
      return FCodePrinter(settings).doprint(expr, assign_to)
  
imports: from __future__ import annotations
  from typing import Any
  from functools import wraps
  from sympy.core import Add, Mul, Pow, S, sympify, Float
  from sympy.core.basic import Basic
  from sympy.core.expr import UnevaluatedExpr
  from sympy.core.function import Lambda
  from sympy.core.mul import _keep_coeff
  from sympy.core.sorting import default_sort_key
  from sympy.core.symbol import Symbol
  from sympy.functions.elementary.complexes import re
  from sympy.printing.str import StrPrinter
  from sympy.printing.precedence import precedence, PRECEDENCE
label_desc: Use image node_id 4 for calling a global function with example usage: fcode(expr, assign_to) and returns: FCodePrinter