The package provides commands for "splitting" a token list at the first
occurrence of another (specified) token list. I.e., for given token lists s, t
return b and the shortest a, such that t = a s b. The package's mechanism
differs from those of packages providing similar features, in the following
ways: the method uses TeX's mechanism of reading delimited macro parameters;
splitting macros work by pure expansion, without assignments; the operation is
carried out in a single macro call. A variant of the operation is provided,
that retains outer braces.
