class_docstr: Turn a vector into a diagonal matrix.
code: def shape(self):
      return self._shape
  
imports: from sympy.core.sympify import _sympify
  from sympy.matrices.expressions import MatrixExpr
  from sympy.core import S, Eq, Ge
  from sympy.core.mul import Mul
  from sympy.functions.special.tensor_functions import KroneckerDelta
label_desc: Use image node_id 2 for calling the DiagMatrix obj's underlying member method code with example usage: obj.shape() and returns: self