Theory of proveit.core_expr_types.lambda_maps

Theory related to Lambda types of Prove-It expressions. A Lambda has parameter(s) and a body and represents a mapping of the parameter(s) to the body. For example, $(x, y) \mapsto x + y$ represents a mapping of $x$ and $y$ into $x + y$; the application of this mapping to the arguments $5$ and $2$ yields $5+2$.