# meta
Read metadata from a function or value.
## Syntax
[meta $value] [meta $value $key]
`$key` optionally reads a single metadata key.
## Examples
[meta $f] # full metadata map [meta $f "doc"] # value of the "doc" key [meta 42] # nil (no metadata)
## Returns
Metadata map (or a specific key's value); nil if the value has no metadata.
## See Also
`with-meta`, `type`, `keys`