The SORT command can sort the list type, collection type, and ordered collection type keys.
The elements in the list are numbers
Operation example: The 
elements are numbers, and the ordered results are returned through the sort command list.
The elements in the list are non-digits
Operation example: 
directly report an error, see the result of the error report, it is impossible to convert to double type, the error is reported. This is because the SORT command will try to convert elements into double-precision floating-point numbers for comparison. Letters cannot be converted into double types, so an error will naturally be reported.
Solution, plus ALPHA parameters
Operation example: It 
can be found that the letters can be sorted normally.