class_docstr: Matrix Trace
  
  Represents the trace of a matrix expression.
  
  Examples
  ========
  
  >>> from sympy import MatrixSymbol, Trace, eye
  >>> A = MatrixSymbol('A', 3, 3)
  >>> Trace(A)
  Trace(A)
  >>> Trace(eye(3))
  Trace(Matrix([
  [1, 0, 0],
  [0, 1, 0],
  [0, 0, 1]]))
  >>> Trace(eye(3)).simplify()
  3
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code: def as_explicit(self):
      return Trace(self.arg.as_explicit()).doit()
  
imports: from sympy.core.basic import Basic
  from sympy.core.expr import Expr, ExprBuilder
  from sympy.core.singleton import S
  from sympy.core.sorting import default_sort_key
  from sympy.core.symbol import uniquely_named_symbol
  from sympy.core.sympify import sympify
  from sympy.matrices.matrixbase import MatrixBase
  from sympy.matrices.exceptions import NonSquareMatrixError
label_desc: Use image node_id 7 for calling the Trace obj's underlying member method code with example usage: obj.as_explicit() and returns: Trace