class_docstr: Class to hold dyadic sums 
class_docstr_tok: ["Class","to","hold","dyadic","sums"]
code: def _sympystr(self, printer):
      items = list(self.components.items())
      items.sort(key=lambda x: x[0].__str__())
      return " + ".join(printer._print(k * v) for k, v in items)
  
imports: from __future__ import annotations
  from sympy.vector.basisdependent import BasisDependent, BasisDependentAdd, BasisDependentMul, BasisDependentZero
  from sympy.core import S, Pow
  from sympy.core.expr import AtomicExpr
  from sympy.matrices.immutable import ImmutableDenseMatrix
  import sympy.vector
label_desc: Use image node_id 2 for calling the DyadicAdd obj's underlying member method code with example usage: obj._sympystr(printer) and returns: str