# Description
`Span` is `Copy`, so we probably should not be passing references of
`Span` around. This PR replaces all instances of `&Span` with `Span`,
copying spans where necessary.
# User-Facing Changes
This alters some public functions to take `Span` instead of `&Span` as
input. Namely, `EngineState::get_span_contents`,
`nu_protocol::extract_value`, a bunch of the math commands, and
`Gstat::gstat`.
583ef8674e