What is John A. Costello?
{{Infobox officeholder | name = John A. Costello | image = US visit of Taoiseach Costello in 1956 (cropped).jpg | order = 3rd | office = Taoiseach | president = [[Seán T. O'Kelly]] | 1blankname = [[Tánaiste]] | 1namedata = [[William Norton]] | term_start = 2 June 1954 | term_end = 20 March 1957 | predecessor = [[Éamon de Valera]] | successor = Éamon de Valera | president1 = Seán T. O'Kelly | 1blankname1 = Tánaiste | 1namedata1 = William Norton | term_start1 = 18 February 1948 | term_end1 = 13 June 1951 | predecessor1 = Éamon de Valera | successor1 = Éamon de Valera | office2 = [[List of Irish Leaders of the Opposition|Leader of the Opposition]] | president2 = Seán T. O'Kelly | taoiseach2 = Éamon de Valera | term_start2 = 20 March 1957 | term_end2 = 21 October 1959 | predecessor2 = Éamon de Valera | successor2 = [[James Dillon (Fine Gael politician)|James Dillon]] | president3 = Seán T. O'Kelly | taoiseach3 = Éamon de Valera | term_start3 = 13 June 1951 | term_end3 = 2 June 1954 | predecessor3 = Éamon de Valera | successor3 = Éamon de Valera | order4 = 3rd | office4 = Attorney General of Ireland | president4 = [[W. T. Cosgrave]] | term_start4 = 9 January 1926 | term_end4 = 9 March 1932 | predecessor4 = [[John O'Byrne]] | successor4 = [[Conor Maguire]] | office5 = [[Teachta Dála]] | term_start5 = [[1948 Irish general election|February 1948]] | term_end5 = [[1969 Irish general election|June 1969]] | constituency5 = [[Dublin South-East (Dáil constituency)|Dublin South-East]] | term_start6 = [[1944 Irish general election|May 1944]] | term_end6 = [[1948 Irish general election|February 1948]] | term_start7 = [[1937 Irish general election|July 1937]] | term_end7 = [[1943 Irish general election|June 1943]] | constituency7 = [[Dublin Townships (Dáil constituency)|Dublin Townships]] | term_start8 = [[1933 Irish general election|January 1933]] | term_end8 =