These functions are user-facing and need docstrings (oops!):

gb.agg.from_string
gb.binary.from_string
gb.indexunary.from_string
gb.monoid.from_string
gb.op.from_string
gb.select.from_string
gb.semiring.from_string
gb.unary.from_string

These are what power strings to be passed in place of operators, such as A.mxm(A, "plus.times") or A.mxm(A, "+.*[int32]").