Guesses the content type based on example data. If the function is
uncertain, result.uncertain will be set to TRUE. Either filename
or data may be NULL, in which case the guess will be based solely
on the other argument.
Usage
gContentTypeGuess(filename, data)
Arguments
filename
a string, or NULL
data
a stream of data, or NULL
Value
A list containing the following elements:
retval
[char] a string indicating a guessed content type for the
given data.