class_docstr: Turn a vector into a diagonal matrix.
code: def _entry(self, i, j, **kwargs):
      if self._iscolumn:
          result = self._vector._entry(i, 0, **kwargs)
      else:
          result = self._vector._entry(0, j, **kwargs)
      if i != j:
          result *= KroneckerDelta(i, j)
      return result
  
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 3 for calling the DiagMatrix obj's underlying member method code with example usage: obj._entry(i, j) and returns: result