Trouble Shooting Psych::SyntaxError

I was getting:
Psych::SyntaxError:
       (): did not find expected key while parsing a block mapping at line 59 column 7
in the yml file.

To troubleshoot use Online YAML Parser  and check which line is having the problem and remove the line to get back to working version. Gradually introduce more text into the yml file to figure out the cause of the problem.