ptpython:tldr:9ae91

This command is using the ptpython command line tool to open an interactive Python shell with the specified Python file as an argument.

Explanation of each part of the command:

• ptpython: This is the command to start the ptpython interactive Python shell. ptpython is an alternative Python interpreter with additional features such as syntax highlighting, auto-completion, and history navigation.
• ${filename-py}: This refers to a variable called filename with the suffix -py appended to it. The ${} is a syntax used by some command interpreters to substitute the value of a variable. In this case, it means that the value of the filename variable with .py appended to it will be used as an argument to ptpython. The actual value of the filename variable depends on the context in which the command is executed.