procedure: indent-tree->range-delimited-tree a indent-char indent-width start-delimiter end-delimiter ->
string char/char-set/procedure integer string string -> string
convert from indent syntax to one where nesting is specified by a pair of strings
for start and end of a range
procedure: line->indent-and-content a indent-width ->
string integer -> (integer string)
procedure: prefix-tree->indent-tree a [base-depth indent-string] ->
list:(string/list ...) -> string
converts a list to a string of indented lines with indent corresponding to nesting depth
procedure: prefix-tree-text source ->
(string/list ...) -> string
convert a list with strings and eventually sub-lists with strings to an indented document structure.
normalise indent from multiline string literals
procedure: read-indent-tree-element->denoted-tree port [indent-width] ->
assumes that unread-string works on the port