return say "Usage: $_{command} [--double] text"
    if $_{msg} eq '' or $_{msg} eq '--help';

local $_ = $_{msg};
tr/A-Za-z/N-ZA-Mn-za-m/ if s/^--double\s*//;
tr/A-Za-z/N-ZA-Mn-za-m/;
tr/\0-\x1F//d;
reply $_;