Reproducing:

Running pdb shell (for example "python -m pdb <some_file.py>"

Input:
x = {'a': 1}
list(x.values())

Output:
*** Error in argument: '(x.values())'

list is a pdb command.

(Pdb) help list
l(ist) [first [,last] | .]

        List source code for the current file.  Without arguments,
        list 11 lines around the current line or continue the previous
        listing.  With . as argument, list 11 lines around the current
        line.  With one argument, list 11 lines starting at that line.
        With two arguments, list the given range; if the second
        argument is less than the first, it is a count.

        The current line in the current frame is indicated by "->".
        If an exception is being debugged, the line where the
        exception was originally raised or propagated is indicated by
        ">>", if it differs from the current line.

You have to use "p list(x.values())" if you want to print the output of the list function.

(Pdb) x = {'a': 1}
(Pdb) p list(x.values())
[1]