code: def is_commutable(expr1, expr2, eps=0.00000001):
      
      return sum((x * x.conjugate()).real for x in commutator(expr1, expr2).coeffs()) < eps
docs: Test whether expr1 and expr2 are commutable.
  
      Args:
          expr1 (Expr, Term or Pauli operator): Pauli's expression.
          expr2 (Expr, Term or Pauli operator): Pauli's expression.
          eps (float, optional): Machine epsilon.
              If |[expr1, expr2]| < eps, consider it is commutable.
  
      Returns:
          bool: if expr1 and expr2 are commutable, returns True, otherwise False.