DocumentationMathematicaBuilt-in FunctionsProgrammingPattern Matching
__ (two _ characters) or BlankSequence[ ] is a pattern object that can stand for any sequence of one or more Mathematica expressions.
__h or BlankSequence[h] can stand for any sequence of one or more expressions, all of which have head h.
See notes for BlankNullSequence.
See Section 2.3.8.
New in Version 1.