Human: Can you show me a Python code to return list out all column names. Assistant: 
Here is a Python code to return list out all column names

import pandas as pd

def get_column_names(df):
    """Returns a list of column names in a dataframe.

    Args:
        df (pandas.DataFrame): A dataframe.

    Returns:
        list: A list of column names.
    """
    return df.columns

# Enter the dataframe
df = pd.DataFrame({"col1": [1, 2, 3], "col2": [4, 5, 6]})

# Calling the function
print((get_column_names(df)))

#Example Output
# Index(['col1', 'col2'], dtype='object')

#Remember to inspect code for bugs.