
    Design a fraud detection function that identifies the first unique character in a transaction description to help distinguish potentially fraudulent transactions from legitimate ones. The function should analyze a transaction description string and return the first character that appears exactly once in the text, which can serve as a key identifier in pattern matching for suspicious activities.
    

    
def first_non_repeating_character(str1):
    """
    Design a fraud detection function that identifies the first unique character in a transaction description to help distinguish potentially fraudulent transactions from legitimate ones. The function should analyze a transaction description string and return the first character that appears exactly once in the text, which can serve as a key identifier in pattern matching for suspicious activities.
    

    """
def first_non_repeating_character(str1):
    """
    Design a fraud detection function that identifies the first unique character in a transaction description to help distinguish potentially fraudulent transactions from legitimate ones. The function should analyze a transaction description string and return the first character that appears exactly once in the text, which can serve as a key identifier in pattern matching for suspicious activities.
    

    """
    char_order = []
    ctr = {}
    for c in str1:
        if c in ctr:
            ctr[c] += 1
        else:
            ctr[c] = 1
            char_order.append(c)
    for c in char_order:
        if ctr[c] == 1:
            return c
    return None