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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def dataframe_to_smp(dataframe,smp_filename,name_col="name", datetime_col="datetime",value_col="value", datetime_format="dd/mm/yyyy", value_format="{0:15.6E}", max_name_len=12):
 """ write a dataframe as an smp file Parameters dataframe : pandas.DataFrame smp_filename : str smp file to write name_col: str the column in the dataframe the marks the site namne datetime_col: str the column in the dataframe that is a datetime instance value_col: str the column in the dataframe that is the values datetime_format: str either 'dd/mm/yyyy' or 'mm/dd/yyy' value_format: str a python float-compatible format """

    formatters = {"name":lambda x:"{0:<20s}".format(str(x)[:max_name_len]),
                  "value":lambda x:value_format.format(x)}
    if datetime_format.lower().startswith("d"):
        dt_fmt = "%d/%m/%Y    %H:%M:%S"
    elif datetime_format.lower().startswith("m"):
        dt_fmt = "%m/%d/%Y    %H:%M:%S"
    else:
        raise Exception("unrecognized datetime_format: " +\
                        "{0}".format(str(datetime_format)))

    for col in [name_col,datetime_col,value_col]:
        assert col in dataframe.columns

    dataframe.loc[:,"datetime_str"] = dataframe.loc[:,"datetime"].\
        apply(lambda x:x.strftime(dt_fmt))
    if isinstance(smp_filename,str):
        smp_filename = open(smp_filename,'w')
        # need this to remove the leading space that pandas puts in front
        s = dataframe.loc[:,[name_col,"datetime_str",value_col]].\
                to_string(col_space=0,
                          formatters=formatters,
                          justify=None,
                          header=False,
                          index=False)
        for ss in s.split('\n'):
            smp_filename.write("{0:<s}\n".format(ss.strip()))
    dataframe.pop("datetime_str")