How do I import modules in the Factor interpreter?

I'm following the Sam's decipher tutorial. When he does 8 group, on my computer Factor gripes that it doesn't know the group function.

( scratchpad ) "01101001001000000110011001110101011000110110101101100101011001000010000001111001011011110111010101110010001000000110110101101111011011010000110100001010011000010110111001100100001000000110111001101111011101110010000001100110011011110111001000100000011110010110111101110101"

--- Data stack:
"0110100100100000011001100111010101100011011010110110010101100..."
( scratchpad ) 8 group
1: 8 group
          ^
No word named “group” found in current vocabulary search path

The following restarts are available:

:1      Use the grouping vocabulary
:2      Use the unix.ffi vocabulary
:3      Use the unix.groups vocabulary
4 :res  Defer word in current vocabulary

Type :help for debugging help.

Apparently group is located in the grouping module, but I don't know how to import the module in the interpreter (something like +m module in Haskell's GHCi).

Solution

In the interpreter, type USE: grouping ; to add a single vocabulary to the search path, or USING: a b c ; to add a list of vocabularies.

Documentation: USE: USING:.