class_docstr: A class for managing a circuit plot.
code: def __init__(self, c, nqubits, **kwargs):
      if not np or not matplotlib:
          raise ImportError("numpy or matplotlib not available.")
      self.circuit = c
      self.ngates = len(self.circuit.args)
      self.nqubits = nqubits
      self.update(kwargs)
      self._create_grid()
      self._create_figure()
      self._plot_wires()
      self._plot_gates()
      self._finish()
  
imports: from __future__ import annotations
  from sympy.core.mul import Mul
  from sympy.external import import_module
  from sympy.physics.quantum.gate import Gate, OneQubitGate, CGate, CGateS
label_desc: Use image node_id 1 to create a new CircuitPlot object  with example: obj = CircuitPlot(c, nqubits)