def is_fasta_header(string):
    """Check if the line is a fasta header.

    :param string: a character string.

    :Example:

    >>> from pygtftk.utils import is_fasta_header
    >>> assert is_fasta_header(">DFTDFTD")

    """
    if string.startswith('>'):
        return True
    else:
        return False
