code: def cuboid(target, throat_length='throat.length',
             throat_diameter='throat.diameter'):
      r
      leng = target[throat_length]
      diam = target[throat_diameter]
      value = leng*diam**2
      return value
docs: r"""
      Calculate throat volume assuing a square cross-section
  
      Parameters
      ----------
      target : OpenPNM Object
          The object which this model is associated with. This controls the
          length of the calculated array, and also provides access to other
          necessary properties.
  
      throat_length and throat_diameter : strings
          The dictionary keys containing the arrays with the throat diameter and
          length values.
  
      Notes
      -----
      At present this models does NOT account for the volume reprsented by the
      intersection of the throat with a spherical pore body.