The definition of the python function combine_docs starts on line 227 in combine_documents/map_reduce.py and ends on line 259.

func-def.txt
Running the above QL script on the latest langchain database produces the values:

func.getMetrics().getNumberOfLines() = 33
func.getMetrics().getNumberOfLinesOfCode() = 27 # Should be 26
func.getMetrics().getNumberOfLinesOfComments() = 2
func.getMetrics().getNumberOfLinesOfDocStrings() = 5

I suspect that the number of blank line in the docstring might be a factor.
The above function contains one blank line in a docstring, while the example below contains two blank lines in a docstring.

The function collapse_docs starts on line 67 in combine_documents/reduce.py and ends on line 96.

The above QL script produces the values:

func.getMetrics().getNumberOfLines() = 30
func.getMetrics().getNumberOfLinesOfCode() = 12 # Should be 14
func.getMetrics().getNumberOfLinesOfComments() = 0
func.getMetrics().getNumberOfLinesOfDocStrings() = 16