- type style-  = | | EscapedDoubleQuotes | the arguments should be enclosed in "double quotes" and are already escaped |  | | SingleQuotes | the arguments should be enclosed in 'single quotes' and have to be escaped |  | | EscapedNoQuotes | the arguments should not be enclosed in quotes and are already escaped |  
 
- quoting style of the arguments 
- val quote : style -> string -> string
- val mk_arg_file : string -> style -> string list -> string