Add -b flag to number only non-empty lines

Author: zohrehKazemianpour

implement-shell-tools/cat/cat.py

@@ -8,11 +8,11 @@
 )
 
 parser.add_argument("-n", "--number", action="store_true", help="Number all output lines")
+parser.add_argument("-b", "--number-nonblank", action="store_true", help="Number non-empty lines only")
 parser.add_argument("path", help="File to read")
 
 args = parser.parse_args()
 
-
 # Read the file 
 with open(args.path, "r") as f: 
     content = f.read()
@@ -29,5 +29,21 @@
         numbered_lines.append(numbered_line)
 
     print("\n".join(numbered_lines))
+
+elif args.number_nonblank:
+    lines = content.split("\n")
+    numbered_lines = []
+    line_number = 0
+    
+    for line in lines:
+        if line.strip() == "":  # Empty line
+            numbered_lines.append(line)  # Don't number it
+        else:  # Non-empty line
+            line_number = line_number + 1
+            numbered_line = f"{line_number:6}\t{line}"
+            numbered_lines.append(numbered_line)
+    
+    print("\n".join(numbered_lines))    
+    
 else:
     print(content)