def batchstack(size, iterable=None, rest=False):
def stack(data):<EOL><INDENT>import numpy as np<EOL>return map(np.vstack, data)<EOL><DEDENT>fn = batchzip(size, rest=rest) >> flow(stack)<EOL>return fn if iterable is None else fn(iterable)<EOL>
todo : add example
:param size:
:param iterable:
:param rest:
:return: