code: def area(triangles=None, crosses=None, sum=False):
      
      if crosses is None:
          crosses = cross(triangles)
      area = (np.sum(crosses**2, axis=1)**.5) * .5
      if sum:
          return np.sum(area)
      return area
docs: Calculates the sum area of input triangles
  
      Parameters
      ----------
      triangles : (n, 3, 3) float
        Vertices of triangles
      crosses : (n, 3) float or None
        As a speedup don't re- compute cross products
      sum : bool
        Return summed area or individual triangle area
  
      Returns
      ----------
      area : (n,) float or float
        Individual or summed area depending on `sum` argument