parameters: (length = '', quantity = '', mass = '', time = '',
            act_energy = '', energy = '', pressure = '')
docstring: Set the default units.
  
      :param length:
          The default units for length. Default: ``'m'``
      :param mass:
          The default units for mass. Default: ``'kg'``
      :param quantity:
          The default units to specify number of molecules. Default: ``'kmol'``
      :param time:
          The default units for time. Default: ``'s'``
      :param energy:
          The default units for energies. Default: ``'J'``
      :param act_energy:
          The default units for activation energies. Default: ``'K'``
      :param pressure:
          The default units for pressure. Default: ``'Pa'``
docstring_summary: Set the default units.
docstring_tokens: Set the default units .
function: def units(length = '', quantity = '', mass = '', time = '',
            act_energy = '', energy = '', pressure = ''):
      """
      Set the default units.
  
      :param length:
          The default units for length. Default: ``'m'``
      :param mass:
          The default units for mass. Default: ``'kg'``
      :param quantity:
          The default units to specify number of molecules. Default: ``'kmol'``
      :param time:
          The default units for time. Default: ``'s'``
      :param energy:
          The default units for energies. Default: ``'J'``
      :param act_energy:
          The default units for activation energies. Default: ``'K'``
      :param pressure:
          The default units for pressure. Default: ``'Pa'``
      """
      global _ulen, _umol, _ue, _utime, _umass, _uenergy, _upres
      if length: _ulen = length
      if quantity: _umol = quantity
      if act_energy: _ue = act_energy
      if time: _utime = time
      if mass: _umass = mass
      if energy: _uenergy = energy
      if pressure: _upres = pressure
function_tokens: def units ( length = '' , quantity = '' , mass = '' , time = '' , act_energy = '' , energy = '' , pressure = '' ) : global _ulen , _umol , _ue , _utime , _umass , _uenergy , _upres if length : _ulen = length if quantity : _umol = quantity if act_energy : _ue = act_energy if time : _utime = time if mass : _umass = mass if energy : _uenergy = energy if pressure : _upres = pressure