Added sympy to mock.
Added sympy to mock.

skidzo/pydy,oliverlee/pydy,skidzo/pydy,oliverlee/pydy,skidzo/pydy,jcrist/pydy,Shekharrajak/pydy,skidzo/pydy,Shekharrajak/pydy,oliverlee/pydy,jcrist/pydy,Shekharrajak/pydy,jcrist/pydy,jcrist/pydy,jcrist/pydy,jcrist/pydy,jcrist/pydy,Shekharrajak/pydy