Method Stdio.File()->openpt()
- Method
openpt
 intopenpt(string(7bit)mode)- Description
 Open the master end of a pseudo-terminal pair. The parameter
modeshould contain one or more of the following letters:"r"Open terminal for reading.
"w"Open terminal for writing.
modeshould always contain at least one of the letters"r"or"w".- See also
 grantpt()