Fix get_type_of_expression for constants like sympy.pi

Problem some constant expressions are neither Float,Integer,Rational but
don't have arguments.

>>> isinstance(pi, Integer)
False
>>> isinstance(pi, Float)
False
>>> isinstance(pi, Rational)
False
>>> pi.args
()
6 jobs for fix-get_type_of_expression-for-constants in 2 minutes and 21 seconds (queued for 2 seconds)