How should indexing by a numeric value in a heterogeneous map with multiple possible matches work?

[hudlow]

If I have a heterogeneous map m = {1: "one", 1u: "two", 1.0: "three"} then what should be the result of m[1], m[1u], and m[1.0]? The spec and conformance tests seem to be silent on this—and somewhat to my surprise—the Go implementation seems to treat heterogeneous comparisons as a fallback such that indexing by the different types yields different values.