This class is used internally by FieldStorage and is not
  meant to be instantiated by the user. Each instance of a Field
  class represents an HTML Form input.
Field instances have the following attributes:
- name
- 
    The input name.
  
- value
- 
    The input value. This attribute can be used to read data from a file
    upload as well, but one has to exercise caution when dealing with
    large files since when accessed via value, the whole file is
    read into memory.
  
- file
- 
    This is a file object. For file uploads it points to a temporary file.
    For simple values, it is a StringIO object, so you can read
    simple string values via this attribute instead of using the value
    attribute as well.
  
- filename
- 
    The name of the file as provided by the client.
  
- type
- 
    The content-type for this input as provided by the client.
  
- type_options
- 
    This is what follows the actual content type in the content-typeheader provided by the client, if anything. This is a dictionary.
- disposition
- 
    The value of the first part of the content-dispositionheader.
- disposition_options
- 
    The second part (if any) of the content-dispositionheader in
    the form of a dictionary.