code: def cylindrical(cls, mag, theta, z=0):
          '''Returns a Vector instance from cylindircal coordinates'''
          return cls(
              mag * math.cos(theta),  # X
              mag * math.sin(theta),  # Y
              z  # Z
          f cylindrical(cls, mag, theta, z=0):
          '''Returns a Vector instance from cylindircal coordinates'''
          return cls(
              mag * math.cos(theta),  # X
              mag * math.sin(theta),  # Y
              z  # Z
          )
docs: Returns a Vector instance from cylindircal coordinates