class_docstr: Holds a growable grid of objects.
  
  Explanation
  ===========
  
  It is possible to append or prepend a row or a column to the grid
  using the corresponding methods.  Prepending rows or columns has
  the effect of changing the coordinates of the already existing
  elements.
  
  This class currently represents a naive implementation of the
  functionality with little attempt at optimisation.
class_docstr_tok: ["Holds","a","growable","grid","of","objects",".","Explanation","===========","It","is","possible","to","append","or","prepend","a","row","or","a","column","to","the","grid","using","the","corresponding","methods",".","Prepending","rows","or","columns","has","the","effect","of","changing","the","coordinates","of","the","already","existing","elements",".","This","class","currently","represents","a","naive","implementation","of","the","functionality","with","little","attempt","at","optimisation","."]
docstr: Appends an empty column to the grid.
docstr_tok: ["Appends","an","empty","column","to","the","grid","."]
code: def append_column(self):
      """
      Appends an empty column to the grid.
      """
      self._width += 1
      for i in range(self._height):
          self._array[i].append(None)
  
imports: from sympy.categories import CompositeMorphism, IdentityMorphism, NamedMorphism, Diagram
  from sympy.core import Dict, Symbol, default_sort_key
  from sympy.printing.latex import latex
  from sympy.sets import FiniteSet
  from sympy.utilities.iterables import iterable
  from sympy.utilities.decorator import doctest_depends_on
  from itertools import chain
label_desc: Use image node_id 7 for calling the _GrowableGrid obj's underlying member method code with example usage: obj.append_column() without return types