code: def _cz_gate(self, lines):
          
          line = lines[0]
          delta_pos = self._gate_offset(Z)
          gate_width = self._gate_width(Z)
          gate_str = self._phase(line, self.pos[line])
  
          for ctrl in lines[1:]:
              gate_str += self._phase(ctrl, self.pos[line])
              gate_str += self._line(ctrl, line)
  
          new_pos = self.pos[line] + delta_pos + gate_width
          for i in lines:
              self.op_count[i] += 1
          for i in range(min(lines), max(lines) + 1):
              self.pos[i] = new_pos
          return gate_str
docs: Return the TikZ code for an n-controlled Z-gate.
  
          :param lines: List of all qubits involved.
          :type: list[int]