class basic_mime_header :(string * string) list ->mime_header
An implementation of mime_header.
The argument is the list of (name,value) pairs of the header.
Example: Create a MIME header with only the field "Content-type":
 let h = new basic_mime_header ["content-type", "text/plain"] Example: Set the field "Subject":
 h # update_field "subject" "The value of this field" This mime_header implementation bases on a mixture of a Map data
 structure and a doubly linked list. The efficiency of the operations
 (n=number of fields; m=average number of values per field; 
 n*m=total number of values):
new, set_fields: O(m * n * log n), but the construction of the dictionary
   is deferred until the first real accessfield: O(log n)multiple_field: O(log n + m)fields: O(n * m)update_field, update_multiple_field: O(log n + m)delete_field: O(n + m)