Given a named nested list returned by kvh_read(), get a particular item from it. The object is identified by a series of hierarchical keys, first key corresponds to the first hierarchical level, the second corresponds to the second and so on.
obj_by_keys(li, keys)
a named nested list returned by kvh_read()
character vector naming key suites to identify an object
an object corresponding to li[[keys[1]][[keys[2]][[...]]. Return NULL if non valid keys.