Clean up Python Embedding scripts

[georgemccabe]

Clean up example Python Embedding scripts so they are easier for users to copy and adapt to their data.

• Removed future imports since they were used to transition from python 2 to 3
• Rearranged logic to be more readable by checking error conditions and exiting if they are not met instead of putting all of the logic to run inside the if statement

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[hsoh-u]

I tested missing argument cases. The modification is 1) switching if and else condition and moving code without modification and 2) removing unused import.