System.True - Manhunter07/MFL GitHub Wiki
Declaration
const True = \built-in\
Description
The True constant in the System package represents the true-value of a boolean expression. It invokes the then-branch when used in a conditional context (ie. in an if statement). This does not mean however that truthy values are limited to exactly this, but it is the one supported by the Boolean type.
System.True is the logical opposit of System.False. Thus, negating one will result in the other.