Lcapy is a Python package for linear circuit analysis. It will only solve linear, time invariant networks. In other words, networks comprised of basic circuit components (R, L, C, etc.) that do not vary with time.
Networks and circuits can be described using netlists or combinations of network elements. These can be drawn semi-automatically.
Lcapy cannot directly analyse non-linear devices such as diodes or transistors although it does support simple opamps without saturation. Nevertheless, it can draw them!
Lcapy uses SymPy (symbolic Python) for its values and expressions and thus the circuit analysis can be performed symbolically. See http://docs.sympy.org/latest/tutorial/index.html for the SymPy tutorial.