General-purpose functions in Documotor

These functions help manage the general flow of the program, or work on multiple data types.

Function	Description
`datasource`	Fetch an entry from a data source.
`datasource_many`	Fetch multiple entries from a data source.
`format`	Format input into a string.
`get_stage_id`	Get the ID of the stage of a template.
`get_stage_name`	Get the name of the stage of a template.
`has_value`	Evaluate argument as bool.
`if`	Execute an action depending on whether a condition is met.
`not_null`	Find first argument that is not null.
`parent`	Retrieve the parent of an entry.
`parse_json`	Parse a JSON token from a string.
`safe_mode`	Guarantee execution of a line.
`safe_not_null`	Return the result of first expression that doesn't resolve to null.
`service`	Fetch information from an external service.
`to_string`	Convert a piece of data to string.
`type`	Find the data type of the argument.
`template`	Get another document from a template inside Documotor.