class_docstr: A helper class to index into a parameter vector.
code: def add_weights(self, name, shape):
      start = self.N
      self.N += np.prod(shape)
      self.idxs_and_shapes[name] = (slice(start, self.N), shape)
  
imports: from __future__ import absolute_import
  from __future__ import print_function
  from builtins import range
  import autograd.numpy
  import autograd.numpy.random
  import autograd.scipy.signal
  from autograd import grad
  import data_mnist
label_desc: Use image node_id 2 for calling the WeightsParser obj's underlying member method code with example usage: obj.add_weights(name, shape) without return types