You could --merge and --chop intervals from one to N sorted BED files into single-base intervals with BEDOPS bedops and a Unix pipe:

$ bedops --merge A.bed ... N.bed | bedops --chop 1 - > answer.bed

The merge step merges overlapping intervals before chopping. This removes duplicates.

If you instead want duplicate single-base intervals where there are overlaps, just replace the merge operation with a union operation:

$ bedops --everything A.bed ... N.bed | bedops --chop 1 - > answer.bed

bedtools makewindows -b in.bed -w 1

 awk  '{S=int($2);E=int($3);while(S<E) {printf("%s\t%d\t%s\n",$1,S,S+1);S++}}'   in.bed

import sys 
with open(sys.argv[1],"r")as bed: 
        for line in bed: 
                #cor=line.strip("\n").split("   ") 
                cor=line.strip("\n").split("\t") 
                for i in range(int(cor[1]),int(cor[2])): 
                        print(cor[0],i,i+1,sep="\t")

Save this script as biostars.py and run python biostars.py input.bed .

There are many working solutions. But as you mentioned bedtools, here is how you do it

cat file.bed | windowMaker -b - -w 1