Opens a pipe to a process executed by running
command on the shell.
mode specifies the
permissions to open the file with, which can only be unidirectional
(that is, for reading or writing only).
mode must be one of the following:
Open file for reading; file pointer will be at beginning of file.
Open file for writing. If the file exists, it will be truncated to zero length; if the file doesn’t already exist, it will be created.
If any error occurs while attempting to open the pipe,
false is returned. If not, the resource
handle for the pipe is returned.