# Functions
CancellableCopy will call the Reader and Writer interface multiple time, in order to copy by chunk (avoiding loading the whole file in memory).
Download downloads a file from the given URL into 'w'.
Execute executes root CLI command.
# Variables
RootCmd containsa the root dmsgcurl command.
# Structs
ProgressWriter prints the progress of a download to stdout.
URL represents a dmsg http URL.