pub const INDEX_READ: &str = "[]";Expand description
The catalog name of the subscript read m[key].
A subscript is dispatched on the receiver’s shape and its arity exactly as a
method is — grid[x, y] is Grid[T] at arity two, m[key] is Map[K, V] at
arity one — so it is a catalog row rather than a second dispatch table. The
spelling is not an identifier, which is what keeps it out of source: the
parser only accepts an Ident after ., so m.[](k) cannot be written, and
nothing in the language can name these rows except the subscript grammar.