Multipart.content_length
You're seeing just the function
content_length, go back to Multipart module for more information.
Specs
content_length(t()) :: pos_integer()
Returns the length of the Multipart message in bytes.
It uses the content_length property in each of the message parts to
calculate the length of the multipart message without reading the entire
body into memory. content_length is set on the Multipart.Part by the
constructor functions when possible, such as when the in-memory binary
or the file on disk can be inspected.
This will throw an error if any of the parts does not have content_length
defined.