def __init__(self, f: sympy.Basic):
init_printing()
self.x = Symbol('x')
self.f_sym_list = f.atoms(Symbol)
if len(self.f_sym_list) != 1:
raise ValueError('Unsupported expresssion.')
elif self.x in self.f_sym_list:
raise ValueError('Use a different Symbol')
self.f = f
(self.f_sym, ) = self.f_sym_list
