code: def is_sqrt(expr):
      """Return True if expr is a sqrt, otherwise False."""
  
      return (
          expr.is_Pow
          and expr.exp.is_Rational
          and abs(expr.exp) is S.Half
      )
  
imports: from sympy.core import Add, Expr, Mul, S, sympify
  from sympy.core.function import _mexpand, count_ops, expand_mul
  from sympy.core.sorting import default_sort_key
  from sympy.core.symbol import Dummy
  from sympy.functions import root, sign, sqrt
  from sympy.polys import Poly, PolynomialError
label_desc: Use image node_id 1 for calling a global function with example usage: is_sqrt(expr) and returns: unknown