code: def freq(b, component, solve_for=None, **kwargs):
      
  
      component_ps = _get_system_ps(b, component)
  
      #metawargs = component_ps.meta
      #metawargs.pop('qualifier')
  
      period = component_ps.get_parameter(qualifier='period', check_visible=False)
      freq = component_ps.get_parameter(qualifier='freq', check_visible=False)
  
      if solve_for in [None, freq]:
          lhs = freq
          rhs = 2 * np.pi / period
  
      elif solve_for == period:
          lhs = period
          rhs = 2 * np.pi / freq
  
      else:
          raise NotImplementedError
  
      return lhs, rhs, {'component': component}
docs: Create a constraint for frequency (either orbital or rotational) given a period.
  
      freq = 2 * pi / period
  
      :parameter b: the :class:`phoebe.frontend.bundle.Bundle`
      :parameter str component: the label of the orbit or component in which this
          constraint should be built
      :parameter str solve_for:  if 'freq' should not be the derived/constrained
          parameter, provide which other parameter should be derived
          (ie 'period')
      :returns: lhs (Parameter), rhs (ConstraintParameter), args (list of arguments
          that were passed to this function)