Logger.debug

You're seeing just the macro debug, go back to Logger module for more information.
Link to this macro

debug(message_or_fun, metadata \\ [])

View Source (macro) (since 1.11.0)

Logs a debug message.

Returns :ok.

Examples

Logging a message (string or iodata):

Logger.debug("this is a debug message")

Report message (maps or keywords):

# as keyword list
Logger.debug([something: :reported, this: :debug])

# as map
Logger.debug(%{something: :reported, this: :debug})