code: def linear_elasticity(grid, spacing=None, E=1e5, nu=0.3, format=None):
      
      if len(grid) == 2:
          return q12d(grid, spacing=spacing, E=E, nu=nu, format=format)
      else:
          raise NotImplemented('no support for grid=%s' % str(grid))
docs: Linear elasticity problem discretizes with Q1 finite elements on a regular rectangular grid.
  
      Parameters
      ----------
      grid : tuple
          length 2 tuple of grid sizes, e.g. (10, 10)
      spacing : tuple
          length 2 tuple of grid spacings, e.g. (1.0, 0.1)
      E : float
          Young's modulus
      nu : float
          Poisson's ratio
      format : string
          Format of the returned sparse matrix (eg. 'csr', 'bsr', etc.)
  
      Returns
      -------
      A : csr_matrix
          FE Q1 stiffness matrix
  
      B : array
          rigid body modes
  
      See Also
      --------
      linear_elasticity_p1
  
      Notes
      -----
          - only 2d for now
  
      Examples
      --------
      >>> from pyamg.gallery import linear_elasticity
      >>> A, B = linear_elasticity((4, 4))
  
      References
      ----------
      .. [1] J. Alberty, C. Carstensen, S. A. Funken, and R. KloseDOI
         "Matlab implementation of the finite element method in elasticity"
         Computing, Volume 69,  Issue 3  (November 2002) Pages: 239 - 263
         http://www.math.hu-berlin.de/~cc/