Update python.md

Adding file managing cheatsheet

python.md

@@ -58,6 +58,7 @@ category: Python
     string.replace("-", " ")
     ",".join(list)
     "hi {0}".format('j')
+    "hi {name}" # same as "hi {}".format('name')
     str.find(",")
     str.index(",")   # same, but raises IndexError
     str.count(",")
@@ -101,3 +102,35 @@ category: Python
     expr.match(...)
     expr.sub(...)
 
+### File manipulation
+    
+    # Reading
+    
+    file = open("hello.txt", "r") #open the file in readmode 'r'
+    file.close() 
+    
+    print(file.read())  # read the file 
+    print fh.readline() # Reading line by line
+    
+    # Writing ( Overwrite the previous content ! )
+    
+    file = open("hello.txt","w") # open the fil in write mode
+    write("Hello World")
+    
+    text_lines = ["First line", "Second line", "a third and last line"] 
+    file.writelines(text_lines) # write the 3 line above inside hello.txt
+    
+    file.close()
+    
+    # Append File 
+    
+    file = open("Hello.txt", "a") #open file in append mode  
+    write("Hello World again")  
+    file.close()
+    
+    # Context Manager
+    
+    with open("welcome.txt" ,"r") as file: # file refer directly to the "welcome.txt" , mode = r , w , a
+       data = file.read()
+       # it close the file automatically no need for file.close()
+