Can I search for text in a function?

Greetings!

Sometimes I need to track down how something happens in the database our
application relies on, but whatever's happening may be buried in some
old function that everybody here has forgotten about long ago. IIRC,
functions are stored internally merely as fields in a table owned by the
system. Is there a query I can use to find what function contains the
string "previous_charge"?

Thank you very much.

Robert D. Richardson
Product Engineer Software

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