BuiltinFloat returns a floating point number held by the native value.

BuiltinInt returns a integer held by the native value.

BuiltinString returns a string held by the native value (it does not convert non-string values to strings).

BuiltinStructField reflects the first argument and returns the named struct field.

LoadPackage adds the time package to env.

DeafultPackageName is the package name used by LoadPackage.