如何在没有评估的情况下定义长符号表达式的实/虚部分？

I'm new to python and am having trouble with sympy. I define complex equations which are functions of the parameters a, b and use hold=true to save computation time. For example I have defined g in terms of other quantities A,B,C,D,E,F, as,I'm new to python and am having trouble with sy