如何使用python获取带条件的顺序计数(以fasta表示)？

def count_sequence_with_condition(fasta_file, condition):
    # 读取fasta文件
    sequences = {}
    with open(fasta_file, 'r') as file:
        lines = file.readlines()

    # 解析fasta文件中的序列
    sequence = ''
    for line in lines:
        if line.startswith('>'):
            if sequence:
                sequences[header] = sequence
                sequence = ''
            header = line.strip()[1:]
        else:
            sequence += line.strip()
    if sequence:
        sequences[header] = sequence

    # 进行顺序计数
    count = 0
    for header, sequence in sequences.items():
        if condition in sequence:
            count += 1

    return count

fasta_file = 'example.fasta'
condition = 'ATG'
count = count_sequence_with_condition(fasta_file, condition)
print(f"带条件'{condition}'的顺序计数为: {count}")