port procedure:{string:line -> (integer:nesting-depth/false string:heading/false)} -> list
procedure: read-outlineport parse-heading ->
port char/procedure:{string:line -> (integer:nesting-depth/false string:heading/false)} -> list
for parsing structured text where repetitions of a character at the beginning of a line designate the section nesting depth of following lines that are not of equal or lower nesting depth