Given a text document, identify every proper noun in it
Elon Musk is the founder of Tesla and SpaceX.
Elon Musk, Tesla, SpaceX.
Complete the following task based on the instruction and optional input provided.### Instruction:
Given a text document, identify every proper noun in it

### Input:
Elon Musk is the founder of Tesla and SpaceX.

### Output:
Elon Musk, Tesla, SpaceX.