code: def cov(x, y, keepdims=0):
      
  
      n = len(x)
      xmn = mean(x)
      ymn = mean(y)
      xdeviations = [0] * len(x)
      ydeviations = [0] * len(y)
      for i in range(len(x)):
          xdeviations[i] = x[i] - xmn
          ydeviations[i] = y[i] - ymn
      ss = 0.0
      for i in range(len(xdeviations)):
          ss = ss + xdeviations[i] * ydeviations[i]
      return ss / float(n - 1)
docs: Returns the estimated covariance of the values in the passed
  array (i.e., N-1).  Dimension can equal None (ravel array first), an
  integer (the dimension over which to operate), or a sequence (operate
  over multiple dimensions).  Set keepdims=1 to return an array with the
  same number of dimensions as inarray.
  
  Usage:   lcov(x,y,keepdims=0)