Finds a NIML node that matches a particular key and value
Parameters:
niml_dict: dict :
NIML dictionary in which the node is to be found
key: str :
Key for a node that is to be found
value: str :
Value associated with key that is to be found
just_one: boolean (default: True) :
Indicates whether exactly one matching node is to be found.
Returns:
nd: dict or list. :
NIML dictionary matching key and value. If just_one is True then, if
a single node is found, it returns a dict containing that node;
otherwise an exception is raised. If just_one is False then the output
is a list with matching nodes; this list is empty if no matching nodes
were found.