exists()

exist() does an existance test on match components.

Unlike a simple reference to a match component, also essentially an existance test, exists() will return True even if there is a value that evaluates to False. I.e. the False is considered to exist for the purposes of matching.

Data signatures
exists( Component to check: $${\color{green}None}$$ ǁ $${\color{green}Any}$$ )

Call signatures
exists( Component to check: Variable ǁ Header ǁ Function ǁ Reference )

Purpose	Value
Main focus	exists() determines if lines match

Context	Qualifier
Match qualifiers	onmatch
Value qualifiers	onmatch

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