我在MATLAB的命令窗口中打exist('map')，输出是7，这是什么意思？

>> help exist
EXIST Check if variables or functions are defined.
EXIST('A') returns:
0 if A does not exist
1 if A is a variable in the workspace
2 if A is an M-file on MATLAB's search path. It also returns 2 when
A is the full pathname to a file or when A is the name of an
ordinary file on MATLAB's search path
3 if A is a MEX-file on MATLAB's search path
4 if A is a MDL-file on MATLAB's search path
5 if A is a built-in MATLAB function
6 if A is a P-file on MATLAB's search path
7 if A is a directory
8 if A is a Java class

>> exist('map')

ans =

7
7 if A is a directory