import csv


def get_reactions(input_file):
    """
    Get all the reactions from the input file

    Reads the input file and gets the reactions that the user might 
    want to add to the universal model. 
    Input file must be in the same folder as the script. 
    The file name must be a string including .csv extension.
    --------------------------------------------------------
    Argument:
    input_file--str input file in .csv format dictionary like

    Return:
    react_IDs: list of BiGG IDs of the reactions to be added to the
        universal model
    """
    with open(input_file, newline='', encoding='utf-8-sig') as csvfile:
        reader = csv.DictReader(csvfile, dialect='excel')
        react_IDs = []
        for row in reader:
            if row['Reaction_ID'] != '':
                r = row['Reaction_ID']
                if '#' not in r:
                    react_IDs.append(r)
    return react_IDs