In computer science, a multimap (sometimes also multihash or multidict) is a generalization of a map or associative array abstract data type in which more than one value may be associated with and returned for a given key. Both map and multimap are particular cases of containers (for example, see C++ Standard Template Library containers). Often the multimap is implemented as a map with lists or sets as the map values - wikipedia 
# Go multihash tool
multihash -h
usage: ./multihash [options] [FILE]
Print or check multihash checksums. With no FILE, or when FILE is -, read standard input.
# Examples Input # from stdin
> multihash < main.go QmRZxt2b1FVZPNqd8hsiykDL3TdBDeTSPX9Kv46HmX4Gx8
# from file
> ./multihash main.go QmRZxt2b1FVZPNqd8hsiykDL3TdBDeTSPX9Kv46HmX4Gx8
# from stdin "filename"
> multihash - < main.go QmRZxt2b1FVZPNqd8hsiykDL3TdBDeTSPX9Kv46HmX4Gx8
# See also - IPFS Multihash - Multimap - IPFS Files - IPFS Paths