added Brace exspansion module (#535)

* updated readme

* added the expand module

* change from --help to -h due to a bug

* changed expand to main, to self reference

* updated wrong output

modules/filesystem/expand.nu

@@ -0,0 +1,64 @@
+
+# A bash like quick string manipulation script
+# the script works by creating a list from brace contents, seperated by a brace.
+
+# Expand the given string into a list on braces like bashes brace expansion 
+export def main [ 
+  input: string   # the string to expand.
+  ] {
+  listify $input
+}
+
+def listify [lst] {
+  try {
+    ($lst 
+      | parse -r '(?P<left>.*)(?<!\\){(?P<list>.*)(?<!\\)}(?P<right>.*)'
+      | get 0
+      | upsert list { |l|
+        $l.list
+        | split row ","
+        | str trim
+      }
+      | each { |it| 
+        $it.list 
+        | each { |l|
+          listify $"($it.left)($l)($it.right)"
+        }})
+    | flatten
+  } catch {
+    $lst
+  }
+}
+
+export def help [] {
+  print -n ( main -h )
+
+  print (
+  [
+    $"(ansi green)Examples(ansi reset):"
+    $"  > (ansi light_green)expand (ansi green)a/{b,c}/d(ansi reset)"
+    $"╭───┬───────╮\n│ 0 │ a/b/d │\n│ 1 │ a/c/d │\n╰───┴───────╯"
+    $"  > (ansi light_green)expand (ansi green)\"my {beautifull,ugly} duckling\"(ansi reset)"
+    $"╭───┬────────────────────────╮\n│ 0 │ my beautifull duckling │\n│ 1 │ my ugly duckling       │\n╰───┴────────────────────────╯"
+    $"  > (ansi light_green)expand (ansi green).config/nushell/config.nu{,on}(ansi reset)"
+    $"╭───┬─────────────────────────────╮\n│ 0 │ .config/nushell/config.nu   │\n│ 1 │ .config/nushell/config.nuon │\n╰───┴─────────────────────────────╯"
+    $"  > (ansi light_green)expand (ansi green)a/{b,c}/{d,e,f,g}  (ansi reset)(ansi purple)|(ansi reset)(ansi light_green) each(ansi reset) (ansi light_green){ |d| (ansi reset)(ansi light_green) mkdir(ansi reset) (ansi purple)$d (ansi reset)(ansi light_green)}(ansi reset);(ansi light_green)tree(ansi reset)"
+    $".
+`-- a
+    |-- b
+    |   |-- d
+    |   |-- e
+    |   |-- f
+    |   `-- g
+    `-- c
+        |-- d
+        |-- e
+        |-- f
+        `-- g
+
+12 directories, 0 files"
+  ] |
+  str join "\n" |
+  nu-highlight
+  )
+}