add md showing basic file handling in python

snippets/python/basic_file_handling.md

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+# Basic File Handling
+
+
+## Writing
+
+Open file in current directory to overwrite file contents. Creates file if it doesn't exist.
+```
+file = open("file.txt", "w")
+file.write("hello earth!")
+```
+File contents:
+```
+hello earth!
+```
+## Reading
+
+Open file for read only. Read entire contents of file.
+```
+file = open("file.txt", "r")
+file_contents = file.read()
+```
+Reads:
+```
+hello earth!
+```
+
+## Appending
+
+Open file for appending. This means the existing file content is kept.
+```
+file = open("file.txt", "a")
+file.write("\nhello universe!") # note:"\n" writes a newline 
+```
+File contents:
+```
+hello earth!
+hello universe!
+```
+## Read file line by line
+
+Make a list holding each line in the file
+```
+file = open("file.txt", "r")
+lines_in_file = file.readlines()
+
+for each_line in lines_in_file:
+    print(each_line)
+```
+prints:
+```
+hello earth!
+hello universe!
+```
+
+## Check if file exists 
+
+```
+from pathlib import Path
+
+file_to_find = Path("file.txt")
+
+if file_to_find.exists():
+    print("file exists") 
+else:
+    print("file not found") 
+```
+
+## Delete file
+
+```
+from pathlib import Path
+
+file_to_delete = Path("file.txt")
+file_to_delete.unlink()
+```