version_info = (6, 4, 2)
pre_info = ''
dev_info = ''

def create_valid_version(release_info, epoch=None, pre_input='', dev_input=''):
    '''
    Creates a pep440 valid version of version number given a tuple integers
    and optional epoch, prerelease and developmental info.

    Parameters
    ----------
    release_info : Tuple(Int)
    epoch : Int, default None
    pre_input : Str, default ''
    dev_input : Str, default ''
    '''

    pep440_err = "The version number is not a pep 440 compliant version number"


    if epoch is not None:
        epoch_seg = str(epoch) + '!'
    else:
        epoch_seg = ''

    release_seg = '.'.join(map(str, release_info))

    _magic_pre =  ['a','b','rc']
    if pre_input!='' and not any([pre_input.startswith(prefix) for prefix in _magic_pre]):
        raise ValueError(pep440_err + "\n please fix your prerelease segment.")
    else:
        pre_seg = pre_input

    if dev_input=='':
        dev_seg = dev_input
    elif not dev_input.startswith('.') and dev_input.startswith('dev'):
        dev_seg = ''.join(['.', dev_input])
    elif dev_input.startswith('.dev'):
        dev_seg = dev_input
    elif dev_input!='':
        raise ValueError(pep440_err + "\n please fix your development segment.")

    if dev_input!='' and not any([dev_seg.endswith(str(n)) for n in range(10)]):
        dev_seg = ''.join([dev_seg,'0'])

    out_version = ''.join([epoch_seg, release_seg, pre_seg, dev_seg])


    import re
    def is_canonical(version):
        return re.match(r'^([1-9]\d*!)?(0|[1-9]\d*)'
                        r'(\.(0|[1-9]\d*))*((a|b|rc)(0|[1-9]\d*))?'
                        r'(\.post(0|[1-9]\d*))?(\.dev(0|[1-9]\d*))?$',
                        version
                        ) is not None

    if is_canonical(out_version):
        return out_version
    else:
        raise ValueError(pep440_err)


__version__ = create_valid_version(version_info, pre_input=pre_info, dev_input=dev_info)
