ENV is a hash-like accessor for environment variables.

Ruby error handling types.

An implementation of MatchData for all Regexp backends.

The Ruby Math module.

Random provides an interface to Ruby’s pseudo-random number generator, or PRNG. The PRNG produces a deterministic sequence of bits which approximate true randomness. The sequence may be represented by integers, floats, or binary strings.

ruby/spec compliant implementation of Regexp.

Time is an abstraction of dates and times.