mathlib3

0ea3dfe4 - feat(tactic/rcases): transport the `cases h : e` syntax to `rcases` (#1611)

feat(tactic/rcases): transport the `cases h : e` syntax to `rcases` (#1611) * Update rcases.lean * Update rcases.lean * Update rcases.lean * Update lift.lean * Update rcases.lean * Update tactics.md * Update rcases.lean