dedent_lines(+In, 
-Out, +Options)\n" -- conversion to and from external forms (such as "\r\n") 
are typically done by the I/O predicates. A final "\n" is 
preserved.
Options:
- tab(N)
 - Assume tabs at columns of with N. When omitted, tabs are taken literally and only exact matches are removed.
 - chars(CodesOrString)
 - Characters to remove. This can notably be used to remove additional 
characters such as 
*or‘|‘. Default is" \t".