Context is a collection of variables and functions that can be used
by the interpreter to resolve expressions. The context can be either
a parent context, or a child context. A parent context is created by
default and contains all of the built-in functions. A child context
can be created by calling .clone(). The child context has it’s own
variables (which can be added to), but it will also reference the
parent context. This allows for variables to be overridden within the
child context while still being able to resolve variables in the child’s
parents. You can have theoretically have an infinite number of child
contexts that reference each-other.