code: def fttest(x, vx):
      """Assuming that x and vx represent a effect and variance estimates,
      returns a cumulated ('fixed effects') t-test of the data over each row
  
      Parameters
      ----------
      x: array of shape(nrows, ncols): effect matrix
      vx: array of shape(nrows, ncols): variance matrix
  
      Returns
      -------
      t array of shape(nrows): fixed effect statistics array
      """
      if np.shape(x) != np.shape(vx):
          raise ValueError("incompatible dimensions for x and vx")
      n = x.shape[1]
      t = x / np.sqrt(np.maximum(vx, 1.0e-15))
      t = t.mean(1) * np.sqrt(n)
      return t
  
imports: import numpy
  from nipy.io.nibcompat import get_affine
  from nipy.labs.spatial_models.discrete_domain import grid_domain_from_binary_array
label_desc: Use image node_id 9 for calling a global function with example usage: fttest(x, vx) and returns: t