code: def solve(self, *args, fn_x=None):
      """
      Solves an equation/optimization for $x$ involving an expression $f(x)$.
  
      Args:
          *args: Additional solver-specific arguments.
          fn_x: A callable returning an expression $f(x)$ given $x$.
  
      Returns:
          A solution $x$ to the problem as given by the solver.
      """
      raise NotImplementedError
  
imports: from tensorforce.core import Module
label_desc: Use image node_id 1 for calling the Solver obj's underlying member method code with example usage: obj.solve() without return types