Parses a new Expression from the given [expression] string.

Similar to [New], except that instead of a string, an already-tokenized expression is given.

Similar to [New], except enables the use of user-defined functions.

Expression represents a set of Tokens which, taken together, are an expression that can be evaluated down into a single value.

Parameters is a collection of named parameters that can be used by an Expression to retrieve parameters when an expression tries to use them.

Represents a function that can be called from within an expression.