I am really new to python and pandas, I am trying to execute a python script using arguments in the command line but I got an error, here is my script

```
 #!/usr/bin/python
 import sys, pandas as pd

 df1 = pd.read_table(sys.argv[0], sep="\t", header=0)
 df2 = pd.read_table(sys.argv[1], sep="\t", header=0)

 df_merge = pd.merge(left=df1, right=df2, left_on=sys.arg[2],  right_on=sys.arg[3])
 df_merge.to_csv(sys.arg[4], sep="\t")

```

And I got the following error: `KeyError: u'no item named file.out'`, any help would be apreciated

My command line statement is: `merge_files.py file1.out file2.out col1 col3 test`